text: /* SPDX-License-Identifier: GPL-2.0
   * Copyright (c) 2018 Facebook
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   */
  #include <linux/bpf.h>
  #include <linux/if_ether.h>
  #include <bpf/bpf_helpers.h>
  
  int _version SEC("version") = 1;
  
  SEC("xdp_adjust_tail")
  int _xdp_adjust_tail(struct xdp_md *xdp)
  {
  	void *data_end = (void *)(long)xdp->data_end;
  	void *data = (void *)(long)xdp->data;
  	int offset = 0;
  
  	if (data_end - data == 54)
  		offset = 256;
  	else
  		offset = 20;
  	if (bpf_xdp_adjust_tail(xdp, 0 - offset))
  		return XDP_DROP;
  	return XDP_TX;
  }
  
  char _license[] SEC("license") = "GPL";
  